The invention relates to a multistage piston compressor for a gaseous or cryogenically liquefied medium with at least two compressor stages, which operatively interact with a shared drive train for purposes of joint powering, wherein each compressor stage exhibits a piston that is mechanically connected with the drive train, and arranged in a compressor cylinder so that it can longitudinally shift.
A generic, multistage piston compressor is known from 10 2006 042 122 A1.
Such compressors are used to compress gaseous or liquid media, such as hydrogen, nitrogen or natural gas in a gaseous or liquid state.
In generic, multistage compressors where the pistons of the individual compressor stages are connected with a shared drive train, and the pistons of the individual compressor stages are mechanically joined with the drive train, the pistons of the compressor stages are jointly powered by the drive train, and with the drive train actuated each perform a piston motion with a constant piston stroke. Each piston of the corresponding compressor stage is exposed to the pressure of the medium built up in the corresponding compressor stage. If a compressor stage concurrently operates without compressor power, for example in a partial load range or no-load state, the built up pressure of the medium on the concurrently operating piston executing the piston stroke creates an additional energy demand, which must be applied by way of the drive train to power the piston. In addition, the built up pressure causes the concurrently operating piston to place a load on the drive train, as a result of which a non-uniform load is placed on the drive train, especially during the partial load operation or no-load operation of a compressor stage. Furthermore, loads and mechanical wear arise on allocated components in the piston of a compressor stage concurrently operating under a partial or no load, for example on the sealing devices for sealing the piston in the compressor cylinder, the mounts of the piston as well as the suction valve and pressure valve of the medium to be compressed. In addition, the piston stroke motion of the concurrently operating piston of a compressor stage produces wear on the corresponding surfaces between the piston and compressor cylinder.
If the compressor stages in a generic, multistage compressor are connected in series as stage compressors, and the output side of a compressor stage is connected with the input of a next compressor stage, the result in a generic compressor in which the pistons of the compressor stages are coupled with a shared drive train and synchronously powered is that the input pressure range and compression ratio of the respective compressor stage are confined to a narrow range by the fixed and constant piston stroke by the piston of the corresponding compressor stage.